1. Field of the Invention
The present invention relates to a recording thin film magnetic head used as, for example, a flying magnetic head, or the like, and particularly, to a thin film magnetic head in which the magnetic path can be shortened to decrease inductance, and withstand voltage between a lower core layer and a coil layer can be improved, and a manufacturing method therefor.
2. Description of the Related Art
FIG. 36 is a partial longitudinal sectional view showing the structure of a conventional thin film magnetic head (inductive head).
In FIG. 36, reference numeral 1 denotes a lower core layer made of a magnetic material such as permalloy, or the like, and a recording region 12 is formed on the lower core layer 1 near the surface facing a recording medium.
The recording region 12 comprises, for example, a gap layer 4 and an upper pole layer 4 made of a magnetic material.
In addition, a coil layer 5 is formed on the rear region of the upper core layer 1, which is behind the recording region in the height direction (the Y direction shown in FIG. 36).
Furthermore, the pitch intervals of a conductor of the coil layer 5 is filled with an insulation layer 11, and an insulation layer 7 made of an organic material or the like is formed on the coil layer 5 and the insulation layer 11.
As shown in FIG. 36, an upper core layer 8 made of permalloy or the like is formed in the region from the recording region 12 to the insulation layer 7 so that the front end 8a of the upper core layer 8 is magnetically connected to the upper top pole layer 4, and the base end 8b is magnetically connected to the lower core layer 1. As shown in FIG. 36, the front end of the upper core layer 8 may be formed at a position shifted backward from the surface facing the recording medium, or exposed from the surface facing the recording medium.
This thin film magnetic head has a construction in which the coil layer 5 is provided behind the recording region 12 in the height direction so that the magnetic path ranging from the upper core layer 8 to the lower core layer 1 can be shortened to decrease inductance, thereby making adaptable to a higher recording density in future.
As shown in FIG. 36, an insulation underlying layer 9 is formed between the coil layer 5 and the lower core layer 1 to maintain electric insulation between the coil layer 5 and the lower core layer 1.
However, the thin film magnetic head shown in FIG. 36 causes the following problems.
Since the coil layer 5 must be formed behind the recording region 12 in the height direction (the Y direction shown in FIG. 36), the insulation underlying layer 9 must be thinly formed between the coil layer 5 and the lower core layer 1, thereby failing to sufficiently maintain withstand voltage between the coil layer 5 and the lower core layer 1.
The insulation underlying layer 9 is thinly formed by sputtering using an inorganic insulating material, for example, such as Al2O3, or the like.
However, in depositing the thin film by sputtering, the insulation underlying layer 9 is easily contaminated with dust particles (impurities) present in a sputtering apparatus to decrease the withstand voltage of the insulation underlying layer 9.
Also, in forming the thin insulation underlying layer 9 by sputtering, pinholes or the like easily occur in the insulation underlying layer 9, thereby further decreasing the withstand voltage.
Conversely, when the thick insulation underlying layer 9 is formed to a thickness sufficient to secure the withstand voltage between the lower core layer 1 and the coil layer 5, and the coil layer 5 is formed so that the upper surfaces of the coil layer 5 and the recording region 12 lie in substantially the same plane, as shown in FIG. 36, the coil layer 5 is thinned, and thus the width dimension T1 of the coil layer 5 must be increased from the viewpoint of decreasing the coil resistance value. Therefore, the magnetic path ranging from the upper core layer 8 to the lower core layer 1 is lengthened to increase inductance, thereby failing to manufacture a thin film magnetic head adaptable to a higher recording density.
Even when the thick insulation underlying layer 9 is formed, the withstand voltage of the insulation underlying layer 9 cannot be effectively improved due to the above-described contamination with dust particles during sputtering.
The present invention has been achieved for solving the above-described problems of a conventional magnetic head, and an object of the present invention is to provide a thin film magnetic head in which the magnetic path can be shortened to decrease inductance, and the withstand voltage between a coil layer and a lower core layer can be improved, and a manufacturing method therefor.
In order to achieve the object, the present invention provides a thin film magnetic head comprising a lower core layer, an upper core layer, a recording region comprising a pole layer and a gap layer located between the lower and upper core layers in the surface facing a recording medium, and a coil layer formed on the rear portion of the lower core layer, which is behind the recording region in the height direction, for inducing a recording magnetic field in the lower core layer, the upper core layer and the recording region, wherein at least an organic insulation underlying layer is interposed between the lower core layer and the coil layer.
In the present invention, the organic insulation underlying layer made of an organic material having high withstand voltage is formed between the lower core layer and the coil layer, thereby effectively improving the withstand voltage between the lower core layer and the coil layer.
Even with the thin organic insulation underlying layer, pinholes less occur to permit the formation of the thin insulation underlying layer having high withstand voltage, as compared with a conventional insulation underlying layer made of an inorganic insulating material.
More specifically, in the present invention, an inorganic insulation underlying layer is formed on the lower core layer, the organic insulation underlying layer is formed on the inorganic insulation underlying layer, and the coil layer is formed on the organic insulation underlying layer.
Alternatively, the organic insulation underlying layer is formed on the lower core layer, the inorganic insulation underlying layer is formed on the organic insulation underlying layer, and the coil layer is formed on the inorganic insulation underlying layer.
Namely, the insulation underlying layer comprising the two layers, i.e., the organic insulation underlying layer and the inorganic insulation underlying layer, is formed between the lower core layer and the coil layer. This can appropriately improve the withstand voltage between the lower core layer and the coil layer, as compared with the conventional insulation underlying layer comprising a single layer.
Where the inorganic insulation underlying layer is a lower layer, and the organic insulation underlying layer is an upper layer, the pinholes formed in the inorganic insulation underlying layer are appropriately filled with the organic insulation underlying layer to effectively improve the withstand voltage.
In the present invention, the inorganic insulation underlying layer is preferably made of at least one inorganic insulating material of AlO, Al2O3, SiO2, Ta2O3, TiO, AlN, AlSiN, TiN, SiN, Si3N4, NiO, WO, WO3, BN, CrN, SiON, and AlSiO.
The organic insulation underlying layer is preferably made of resist or polyimide.
In the present invention, the thickness of the inorganic insulation underlying layer is preferably in the range of 0.15 xcexcm to 0.5 xcexcm.
The thickness of the organic insulation underlying layer is preferably in the range of 0.2 xcexcm to 1.0 xcexcm.
Furthermore, in the present invention, the gap between the lower core layer and the coil layer is preferably in the range of 0.35 xcexcm to 1.5 xcexcm. With the large gap between the lower core layer and the coil layer, i.e., the thick organic insulation underlying layer or the thick insulation underlying layer comprising the two layers including the organic insulation underlying layer and the inorganic insulation underlying layer, the coil layer must be thinly formed on the insulation underlying layer. In this case, the width dimension of the coil layer must be increased from the viewpoint of decreasing the coil resistance value, and thus the magnetic path ranging from the lower core layer to the upper core layer is lengthened to increase inductance, thereby failing to manufacture a thin film magnetic head adaptable to a future higher recording density.
In the present invention, therefore, the gap between the lower core layer and the coil layer is set to a small value in the above range to permit the formation of the coil layer having a thickness in the same level as a conventional layer, and thus the magnetic path can be shortened to permit the formation of a thin film magnetic head adaptable to a higher recording density.
The gap between the lower core layer and the coil layer has a thickness corresponding to the conventional insulation underlying layer comprising a single layer of an inorganic insulating material.
In the present invention, the pitch intervals of the conductor which constitutes the coil layer may be filled with a coil insulation layer, or coil forming grooves of the coil insulation layer, which is formed on the rear portion of the lower core layer behind the recording region in the height direction, may be filled with the coil layer.
In this case, the upper surface of the coil insulation layer and the upper surface of the coil layer preferably lie in the same plane.
In addition, the upper surfaces of the coil insulation layer and the coil layer are preferably polished.
Furthermore, assuming that the junction plane between the recording region and the upper core layer is a reference plane, the upper surfaces of the coil insulation layer and the coil layer are preferably located in the same plane as the reference plane.
In the present invention, the coil insulation layer is preferably made of an inorganic insulating material.
In the present invention, preferably, an insulation layer is formed on the coil layer, and a second coil layer is formed on the insulation layer so as to be electrically connected to the coil layer, for inducing a recording magnetic field in the lower core layer, the upper core layer and the recording region. This can more effectively realize the short magnetic path ranging from the lower core layer to the upper core layer, thereby permitting the manufacture of a thin film magnetic head adaptable to a higher recording density in future.
In the present invention, the recording region preferably comprises a lower pole layer connected directly to the lower core layer, and a gap layer formed on the lower pole layer, an upper pole layer formed on the lower core layer with a gap layer provided therebetween to be connected directly to the upper core layer, or a lower pole layer connected directly to the lower core layer, and an upper pole layer formed on the lower core layer with a gap layer provided therebetween to be connected directly to the upper core layer.
In this case, the gap layer is preferably made of a nonmagnetic metal material which can be plated.
As the nonmagnetic metal material, at least one material is preferably selected from NiP, NiPd, NiW, NiMo, Au, Pt, Rh, Pd, Ru, Cr, and NiCu.
In the present invention, the recording region may comprise a gap layer formed on the lower core layer, and an upper pole layer formed on the gap layer, or a gap layer which is formed on a protrusion formed integrally with the lower core layer to project toward the upper core layer, and an upper pole layer formed on the gap layer.
In this case, the gap layer is preferably made of an inorganic insulating material. As the inorganic insulating material, at least one material is preferably selected from Al2O3, SiO2, SiON, AlN, AlSiN, and AlSiO.
A method of manufacturing a thin film magnetic head of the present invention comprises:
(a) the step of forming a recording region comprising a pole layer and a gap layer on a lower core layer;
(b) the step of forming an organic insulation underlying layer on the portion of the lower core layer, which is behind the recording region in the height direction;
(c) the step of forming a coil layer and a coil insulation layer on the organic insulation underlying layer so that the coil insulation layer is contained in the pitch intervals of a conductor of the coil layer; and
(d) the step of forming an insulation layer on the coil layer and the coil insulation layer, and then forming an upper core layer on the insulation layer.
In the present invention, after the recording region is formed on the lower core layer, the organic insulation underlying layer can be formed on the portion of the lower core layer, which is behind the recording region in the height direction. The organic insulation underlying layer has higher withstand voltage than an inorganic insulation underlying layer.
In the present invention, the coil layer is formed on the organic insulation underlying layer to appropriately improve the withstand voltage between the lower core layer and the coil layer, as compared with a conventional inorganic insulation underlying layer comprising a single layer.
Particularly, even when the insulation underlying layer made of the organic insulating material is thin, pinholes less occur, thereby facilitating the formation of the thin organic insulation underlying layer. Therefore, the coil layer formed on the organic insulation underlying layer can be made thin to realize the short magnetic path, permitting the manufacture of a thin film magnetic head adaptable to a higher recording density.
The present invention may comprise the following steps in place the above step (b).
(e) The step of forming an inorganic insulation underlying layer in the region from the recording region to the lower core layer; and
(f) The step of forming an organic insulation underlying layer on the inorganic insulation underlying layer formed on the lower core layer.
Alternatively, the present invention may comprise the following steps in place of the step (c).
(g) The step of forming an inorganic insulation underlying layer in the region raging from the recording region to the organic insulation underlying layer; and
(h) The step of forming a coil insulation layer on the inorganic insulation underlying layer to insert the coil insulation layer in the pitch intervals of a conductor of the coil layer.
Namely, in this case, not only the organic insulation underlying layer but also the inorganic insulation underlying layer are formed between the lower core layer and the coil layer.
The two-layer structure comprising the inorganic insulation underlying layer and the organic insulation underlying layer can further improve the withstand voltage, as compared with the single-layer structure of the conventional inorganic insulation layer.
When the organic insulation underlying layer is laminated on the inorganic insulation underlying layer, the organic insulation underlying layer has the function to fill the pinholes formed in the inorganic insulation underlying layer, appropriately improving the withstand voltage.
In the present invention, the inorganic insulation underlying layer is preferably made of at least one inorganic insulating material selected from AlO, Al2O3, SiO2, Ta2O5, TiO, AlN, AlSiN, TiN, SiN, Si3N4, NiO, WO, WO3, BN, CrN, SiON, and AlSiO.
The organic insulation underlying layer is preferably made of resist or polyimide.
In the above step (c) or (h), after the coil insulation layer is formed on the organic insulating underlying layer or the inorganic insulation underlying layer, coil forming grooves are preferably formed in the coil insulation layer so that the coil forming grooves are filled with a conductive material to form the coil layer.
Alternatively, in the step (c) or (h), after the coil layer is formed on the organic insulating underlying layer or the inorganic insulation underlying layer, the pitch intervals of the conductor of the coil layer are preferably filled with the coil insulation layer.
In another aspect of the present invention, there is provided a method of manufacturing a thin film magnetic head comprising:
(i) the step of forming an organic insulation underlying layer at a predetermined position on a lower core layer;
(j) the step of forming a coil insulation layer on the lower core layer and the organic insulation underlying layer;
(k) the step of forming a trench within a predetermined length from the surface of the coil insulating layer facing a recording medium in the height direction, and forming a recording region comprising a gap layer and a magnetic layer in the trench;
(l) the step of forming coil forming grooves in the coil insulation layer on the organic insulation underlying layer, and filling the coil forming grooves with a conductive material to form a coil layer; and
(m) the step of forming an insulation layer on the coil layer and the coil insulation layer and then forming an upper core layer on the insulation layer.
In the present invention, the organic insulation underlying layer is first formed on the lower core layer, the coil insulation layer and the recording region are then formed, and the coil layer is further formed.
In the above-described manufacturing method, the organic insulation underlying layer is formed to appropriately improve the withstand voltage between the lower core layer and the coil layer, and the organic insulation underlying layer can be used as a stopper layer in forming the coil forming grooves in the coil insulation layer in the step (1), permitting the proper formation of the coil layer on the organic insulation underlying layer.
The present invention may comprise the following steps in place the above step (j).
(n) The step of forming an inorganic insulation underlying layer on the organic insulation underlying layer and the lower core layer; and
(o) The step of forming a coil insulation layer on the inorganic insulation underlying layer.
Alternatively, the present invention may comprise the following steps in place of the steps (i) and (j)).
(p) The step of forming an inorganic insulation underlying layer on the lower core layer;
(q) The step of forming an organic insulation underlying layer at a predetermined position on the inorganic insulation underlying layer; and
(r) The step of forming a coil insulation layer on the inorganic insulation underlying layer and the organic insulation underlying layer.
Namely, in this case, not only the organic insulation underlying layer but also the inorganic insulation underlying layer are formed to form a two-layer structure insulation underlying layer.
In the present invention, in the step (a) or (k), the recording region preferably comprises a lower pole layer and a gap layer, a gap layer and an upper pole layer, or a lower pole layer, a gap layer and an upper pole layer.
In this case, the gap layer is preferably made of a nonmagnetic metal material which can be plated together with the pole layers. As the nonmagnetic metal material, at least one material is preferably selected from NiP, NiPd, NiW, NiMo, Au, Pt, Rh, Pd, Ru, Cr, and NiCu.
In the present invention, in the step (a), the recording region may comprise a gap layer and an upper pole layer, or after the recording region is formed, a protrusion may be formed integrally with the lower core layer by grinding both sides of the recording region and the surface of the lower core layer to project from the lower core layer toward the recording region and continue from the recording region.
In this case, the gap layer is preferably made of an inorganic insulating material. As the inorganic insulating material, at least one material is preferably selected from Al2O3, SiO2, SiON, AlN, AlSiN, and AlSiO.
In the present invention, in the step (c), (h) or (l), after the coil layer and the coil insulation layer are formed, the upper surfaces of the coil layer and the coil insulation layer are preferably ground so that assuming that the upper surface of the recording region is a reference plane, the upper surfaces of the coil insulation layer and the coil layer lie in substantially the same plane as the reference plane.
In the present invention, the coil insulation layer is preferably made of an inorganic insulating material.
Also, in the step (d) or (m), after the insulation layer is formed on the coil layer and the coil insulation layer, a second coil layer is preferably formed on the insulation layer so as to be electrically connected to the coil layer, and the upper core layer is then formed on the second coil layer with an insulation layer provided therebetween. This can realize the shorter magnetic path to decrease inductance, thereby permitting the manufacture of a thin film magnetic head adaptable to a higher recording density in future.